There are 3 series, and hence 27 possible permutations left (each series has 3 outcomes).
In 18 of these cases (the branches where Vega does not win 2-0), Liquid qualifies along with Imperial. Liquid have 8 points at the moment, Vega can have at most 7 points (remember they can't win 2-0 in this branch) and Imperial has at least 8 points (if Vega doesn't win 2-0, it means Imperial get at least one point from that series).
In the 9 other cases (the branch where Vega wins 2-0), Vega gets 8 points (tying with Liquid), and in every single case Vega does well enough in the tiebreaker to qualify. In 8 of these 9 cases, it's Imperial who qualifies along with vega
This reduces to: 1/27 permutations: Liquid & Vega qualify. 8/27 permutations: Vega & Imperial qualify.